KR101838917B1 - Method for processing a dental image, apparatus and computer program therefor - Google Patents

Abstract

The present invention relates to a method of processing an oral image, which is based on a plurality of foci in photographing the inside of the mouth, performs curve fitting based on a plurality of foci in processing a photographed image, calculates a deflection value By performing the deflection process, aliasing can be removed from the three-dimensional image. Further, according to the present invention, the calculation speed can be improved by simplifying the calculation to a linear function in calculating the deflection value.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an oral image processing method,

The present invention relates to a method of processing an oral image, and more particularly, to an oral image processing method capable of enhancing an image processing speed by processing an oral image by a bias correction processing method, and an apparatus and a computer program therefor.

It is very useful to use data such as three-dimensional images of oral structures in dental treatment. Accordingly, the dentist is actively using the three-dimensional image of the oral structure, such as a tooth, in that the patient can visually show an immediate treatment course or direction.

An optical three-dimensional scanner is used to acquire three-dimensional images. Specifically, it is possible to measure oral structures such as teeth or gums using an optical three-dimensional camera, and design and manufacture dental prostheses using a CAD / CAM system.

Typically, the 3D image is point cloud data (PCD). There are many ways to acquire a 3D PCD using an oral scanner, and the stereoscopic vision method, which is a typical method, uses an image obtained from two or more cameras. However, in the case of the stereo vision method, it was difficult to find the same point on the epipolar line of each image. 3D PCD can not be obtained if the same point is not found in the equipotential line. In addition, a deviation of each image may occur largely according to the position, the focus state, and the exposure state of each camera, and it may become impossible to find the same point even if there is a surface reflection (glare) on the subject or a fringe pattern.

Structured light is used to solve this problem. However, the method using the structured light is limited by the limitation of the scan area, the limitation of the instrument size, the sensitivity of the surface material, and the necessity of a specific light source.

Korean Patent Publication No. 10-2015-0059472

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is an object of the present invention to improve the quality of a three-dimensional image by obtaining a three-dimensional image using a depth-of-defocus / focus (DFD) As a technical problem.

Other features and advantages of the invention will be set forth in the description which follows, or may be obvious to those skilled in the art from the description and the claims.

A method of processing an oral image according to an exemplary embodiment of the present invention includes: photographing an inside of a mouth based on a plurality of focal points; Image-processing the photographed image; And outputting a three-dimensional image based on the imaged image, wherein the step of image processing the imaged image comprises: performing curve fitting based on the plurality of foci; And calculating a deflection value for the deflection correcting process.

In an embodiment of the present invention, the step of calculating the deflection value comprises: setting a focus having a maximum focus measurement value as a reference focus f _p ; Sampling _{- (n -1 ...} f _p f _p) and a plurality of focus (f _{1 ...} f _{p + p + n)} and after the said reference focus (f _p) to the center of the previous plurality of focus The method comprising the steps of:

In an embodiment of the present invention, the step of calculating the deflection value may include calculating a value of the focus of the sampled focus by using the square (y ² _{p - n ...} y ² _{p -1} , y ² _{p + 1 ...} y ² _{p + n} ); And summing squared values for a plurality of foci before the reference focal point (S ₀ = y ² _{p - n} + _... y ² _{p -1} ), and summing squared values for a plurality of foci after the reference focal point (S ₁ = y ² _{p + 1} + _... y ² _{p + n} ).

이고, A는 편향 계수일 수 있다.In the embodiment of the present invention, the step of calculating the deflection value may include determining the deflection value as max (-1, (R-1) * A) when the sum S ₁ is smaller than S ₀ Further comprising

, And A can be a deflection coefficient.

이고, A는 편향 계수일 수 있다.In the embodiment of the present invention, the step of calculating the deflection value may include determining that the deflection value is min (1, - (R-1) * A) when the summing result S ₁ is _greater than S ₀ Further comprising

, And A can be a deflection coefficient.

In the embodiment of the present invention, the image processing of the photographed image may further include: performing a bi-lateral filter processing for edge preservation and noise suppression of a video image.

A computer program according to an embodiment of the present invention may be a computer program stored in a medium for performing the above-described steps.

An apparatus for processing an oral image according to an embodiment of the present invention includes: a body; head; And a cover, the body comprising: a light output section for imaging the interior of the mouth based on a plurality of foci; An image sensing unit for acquiring a photographed image; And a control unit for controlling the light output unit and the image sensing unit, wherein the control unit performs curve fitting based on the plurality of focuses on the image to process the photographed image, performed to calculate the deflection values for the process, by setting the focus with the maximum focus measurement value of the reference focus (f _p) to calculate the bias value, a previously with respect to the reference focus (f _p) a plurality of _focus-sample the (f _p f _n ... _{p -1)} and a plurality of focus since the _{(p +} f ₁ ... f _{n + p),} and squaring the focus measurement value of the sampled focus ( y ² _{p - n,} y ² _{p -1} , y ² _{p + 1} ... y ² _{p + n} ), summing squared values for a plurality of foci before the reference focal point (S ₀ = y ^{_{2 p - n + ... y 2}} p -1), summing the squared values of the plurality of focus since the focus criteria, and (S ₁ = y ² _{+ p 1} + _p ² ₊ ... y _n ), And if the sum S ₁ is less than S ₀ , the deflection value is determined as max (-1, (R-1) * A). If the sum S ₁ is _greater than S ₀ , min (1, - (R-1) * A). In order to image the photographed image, a bilateral filter process may be performed for edge preservation and noise suppression of the image.

The method, apparatus and computer program for oral image acquisition and processing according to embodiments of the present invention help improve the manner of evaluating the degree of focus in analyzing acquired three-dimensional images.

The present invention also helps to improve the quality of acquired images.

The present invention also helps to simplify the calculation to a linear function and to improve the calculation speed in deriving the deflection value.

The present invention also helps to minimize the number of focuses to be calculated for deriving the deflection value.

In addition, other features and advantages of the present invention may be newly understood through embodiments of the present invention.

1 is a diagram illustrating a method of acquiring an oral image according to an embodiment of the present invention.
2 shows a DOF trend graph according to an embodiment of the present invention.
3 is a view showing a configuration of a liquid lens driver.
4A to 4C are views for explaining a method of measuring the contrast value in the image processing step of the embodiment of the present invention.
5A is a diagram showing an image obtained through image processing.
FIG. 5B is a view showing an image in which a depth alignment process is performed on the image of FIG. 5A. FIG.
6 is a view showing another image in which a depth alignment process is performed.
7 is a diagram showing an image in which an image spreading process is performed.
8 is a view for explaining a curve fitting process.
FIG. 9 is a diagram for explaining a method of deriving a deflection value according to an embodiment of the present invention.
10 is a diagram showing an image in which image texturing processing is performed.
11 is a view schematically showing an oral scanner according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art to which the present invention pertains. The present invention may be embodied in many different forms and is not limited to the embodiments described herein.

In order to clearly illustrate the present invention, parts not related to the description are omitted, and the same or similar components are denoted by the same reference numerals throughout the specification.

Throughout the specification, when a part is referred to as being "connected" to another part, it includes not only "directly connected" but also "electrically connected" with another part in between . Also, when an element is referred to as "comprising ", it means that it can include other elements as well, without departing from the other elements unless specifically stated otherwise.

If any part is referred to as being "on" another part, it may be directly on the other part or may be accompanied by another part therebetween. In contrast, when a section is referred to as being "directly above" another section, no other section is involved.

The terms first, second and third, etc. are used to describe various portions, components, regions, layers and / or sections, but are not limited thereto. These terms are only used to distinguish any moiety, element, region, layer or section from another moiety, moiety, region, layer or section. Thus, a first portion, component, region, layer or section described below may be referred to as a second portion, component, region, layer or section without departing from the scope of the present invention.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms as used herein include plural forms as long as the phrases do not expressly express the opposite meaning thereto. Means that a particular feature, region, integer, step, operation, element and / or component is specified and that the presence or absence of other features, regions, integers, steps, operations, elements, and / It does not exclude addition.

Terms indicating relative space such as "below "," above ", and the like may be used to more easily describe the relationship to other portions of a portion shown in the figures. These terms are intended to include other meanings or acts of the apparatus in use, as well as intended meanings in the drawings. For example, when inverting a device in the figures, certain portions that are described as being "below" other portions are described as being "above " other portions. Thus, an exemplary term "below" includes both up and down directions. The device can be rotated by 90 degrees or rotated at different angles, and terms indicating relative space are interpreted accordingly.

Unless otherwise defined, all terms including technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Commonly used predefined terms are further interpreted as having a meaning consistent with the relevant technical literature and the present disclosure, and are not to be construed as ideal or very formal meanings unless defined otherwise.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

1 is a diagram illustrating a method of acquiring an oral image according to an embodiment of the present invention.

Referring to FIG. 1, the process of obtaining an oral image includes an intraoral imaging step S110, an image processing step S120, a scanner position guiding step S130, and a data processing step S140.

The intraoral imaging step S110 is a step of photographing teeth or gums in the oral cavity using an oral scanner. In the intraoral imaging step S110, the optical part of the oral scanner is used. The optical part includes a lens capable of moving the focal point, and a method in which the focal length is changed by physically moving the lens may be used, or a method in which the focal length is adjusted by changing the surface shape of the fluid lens with a voltage may be used.

Alternatively, the optics may be replaced by stereo vision based, in which case at least two liquid lenses may be arranged in a horizontal or vertical symmetrical position. Specifically, the image used in the DFD should be included between 1/2 HFD (Hyper focal distance) and infinity (infinity), and the depth of the included area is defined as follows: Respectively.

Total DOF = FarpointDOF - NearpointDOF

[c] Circle of Confusion

[s] Working Distance

[f] Focal Length

[F] F Number

The thinner the depth, the more clearly the prediction of the depth through the focus measurement method becomes, and the design parameters of the lens can be adjusted so that such results can be obtained.

FIG. 2 shows a DOF (Depth of Field) tendency graph. It can be seen that the DOF changes proportionally or inversely to the working distance (s) and F number (F). Therefore, the working distance (s) and F number (F) can be adjusted to make the depth less than 200 μm. The graph (a) of FIG. 2 is a diagram showing the change of the Farpoint DOF according to the change of the working distance (s). As can be seen in the graph, the Farpoint DOF is about 0.16 [mm] when the working distance (s) is 150 [mm] and the Farpoint DOF increases with increasing working distance (s). This change is also true for the near point DOF and can be seen in the graph (d) of FIG. In FIG. 2, graph (b) shows the change of farpoint DOF according to the change of focal length (f). As shown in the graph, the farpoint DOF is about 3.5 [mm] when the focal length (f) is 15 [mm], and the farpoint DOF is decreased as the focal length (f) is increased. This change is also true for the near point DOF and can be seen in the graph (e) of FIG. 2 (c) is a graph showing the change of Farpoint DOF according to the change of F number (F). As shown in the graph, the farpoint DOF is about 0.28 [mm] when F number (F) is 1.1 [mm], and the Farpoint DOF increases with increasing F number (F). This change is also true for the near-point DOF and can be seen in the graph (f) of FIG.

Because of the nature of the oral scanner, the subject is usually located in close proximity, so it is advantageous to have a short hyperfocal distance (HFD). The definition of HFD is as follows.

Where,

In the image processing step S120, the distance information from the lens to all the photographing points can be obtained by a method based on the design numerical value and statistical information of the lens using the DFD method. In order to perform the DFD, the variable focal length f of the lens must be moved at regular intervals and images having n focal points must be obtained. Specifically, it is possible to use a method of determining the optimum focus direction by changing the contrast of each depth image of a predetermined depth section photographed by the liquid lens, and then changing the position of the focus of the liquid lens, Images can be acquired.

That is, the focal distance of the liquid lens is swept, and the contrast value of the photographed image is measured at predetermined intervals. The focal length of the liquid lens is adjusted by applying a pulse width modulation (PWM) voltage corresponding to each diopter through a liquid lens driver.

The structure of the liquid lens driver shown in FIG. 3 shows a structure of a general liquid lens driver, and a detailed description thereof will be omitted. Meanwhile, the liquid lens and its driving method described in FIG. 3 have typical meaning as a representative example for using depth from defocus / focus (DFD), and the scope of the present invention is not limited thereto. It should be understood that the scope of the present invention is also applicable to other ways in which a DFD can be used, including liquid lenses.

On the other hand, the contrast value can be known by dividing the intensity of the center pixel and the brightness of the surrounding pixels by a 3 × 3 convolution mask and dividing the brightness by the window size J × K in which the convolution is performed . The contrast value measurement method can refer to only the cross-shaped portion in the 3 × 3 region (FIG. 4A), the X-shaped portion alone (FIG. 4B), or the entire region (FIG.

If the measured contrast value is equal to or more than the threshold value, the process proceeds to the data processing step S140 and is reconstructed into a three-dimensional image. On the other hand, if the measured contrast value is less than or equal to the threshold value, it is determined that the surface of the object is not included in the focal length [A B] diopter due to the lens specification, and the user is guided to adjust the position of the oral scanner (S 130). Alternatively, if the measured contrast value is less than or equal to the threshold value, the data processing step S140 may be skipped to improve the progress speed. Specifically, the range of the object that actually enters the in-focus region in the range for changing the focal distance can be small. Therefore, if the data processing step (S140) is performed also for the out-focus area, the processing time is delayed accordingly.

In the oral-scanner-position guiding step S130, when it is determined that the image photographed in the image processing step S120 is out-focus, it is indicated that the user is to change the position of the oral-type scanner.

For example, it may indicate to change the location of the oral scanner closer to the object, or to change it away from the object. For example, if A is greater than B and the contrast value A at the maximum distance of focus is compared with the contrast value B at the minimum distance of focus, then the object is outside the focus area, Quot; means far away from the object, thus indicating that the position of the mouth scanner is to be moved closer to the object. In the opposite case, it may indicate that the position of the oral scanner is to be changed away from the object. The movement information can be displayed on a liquid crystal display (LCD) attached to the outside of the mouth scanner, or an alarm system can be used.

The data processing step S140 is a step of processing the image obtained in the image processing step S120. More specifically, the data processing step S140 includes a depth filtering process, a depth filtering process, an image spreading process, a curve fitting process, a bilateral filter process, texturing process.

For example, the image obtained in the image processing step S120 may be as shown in FIG. 5A (Aliased image). Referring to FIG. 5A, an image is acquired for the first time. However, in this image, there is a so-called aliasing in which the boundary line of objects is not smooth but is viewed in a rectangular shape. A depth alignment process can be performed to eliminate such aliasing. The depth alignment process can be performed using, for example, a Gaussian low pass filter. The image obtained after performing the depth alignment process may be as shown in FIG. 5B (Depth aligned image). Referring to FIG. 5B, it can be seen that an image in which aliasing is arranged is obtained when compared with the image of FIG. 5A. However, despite the depth alignment process, aliasing is not completely eliminated and still exists in some areas. FIG. 6 also shows another image in which the alignment process is performed. As can be seen in FIG. 6, aliasing is not completely removed even though the depth alignment process has been performed. In order to generate an accurate image by removing aliasing, a depth spreading process has to be performed, and a depth spreading process is performed through a curve fitting process. The image in which the depth spreading process is performed may be as shown in FIG. 7 (Spreaded depth). Referring to FIG. 7, when compared with FIG. 6, aliasing is considerably eliminated and the surface of the object is precisely represented.

The curve fitting process will now be described with reference to FIG.

와 같은 1차 함수가 이용되고, 3개의 포인트를 연결하기 위해

와 같은 2차 함수가 이용되고, 4개의 포인트를 연결하기 위해

와 같은 3차 함수가 이용된다.Curve fitting refers to creating a smooth curve by connecting a plurality of data points. The curve fitting may include interpolation for estimating a value between a plurality of data points, and may include smoothing using a smoothing function. For example, to connect two points

Are used, and to connect the three points

Are used, and to connect the four points

Is used.

Further, the curve fitting process may include a bias process. The deflection processing means that the deviation is corrected when the curve generated by using the measured data is deflected to either the left or the right. For example, referring to FIG. 8, the x-axis is a focus index and the y-axis is a focus measurement value. As shown in FIG. 8, the actually measured data (original index) using the oral scanner has a maximum value in the x-axis index 5 and is biased to the right with reference to the maximum value index 5. Applying 0.435 as a value (deflection value) for correcting the deviation by performing the curve fitting on the basis of this measured value as shown in the example of FIG. 8, the curve having the maximum value at 4.565 on the x- Biased index) can be generated.

However, according to the conventional technique, the calculation time of such a curve fitting is long. Specifically, according to the conventional technique, a cubic equation or a trigonometric function is used for curve fitting, and a high-order equation or a trigonometric function increases processing time due to the complexity of the calculation process. Accordingly, the present invention proposes an algorithm that can derive a deflection value using a simplified linear function.

In FIG. 8, only seven x-axis focus indexes are shown for explanatory convenience. However, when the number of focus indexes to be calculated is larger, the calculation speed becomes slower. In actual use of the oral scanner, Is generally used. Accordingly, the present invention proposes an algorithm capable of deriving a deflection value using only a minimized number of foci.

Referring to FIG. 9, a method of deriving a deflection value according to an embodiment of the present invention will be described.

First, a step (S710) of setting, based on the focus has the maximum value of the focus measurement focus (f _p) is performed. For example, in FIG. 8, the reference focus having the maximum focus measurement value is index 5.

Based on the focus (f _p) of the plurality of focus before around the _(p f _- f _n ... _{p -1)} and a plurality of focus since the _{(p +} f ₁ ... f _{p + n)} the sampling (S720) is performed. That is, the previous n focuses are sampled about the reference focus, and the following n focuses around the reference focus are sampled so that a total of 2n focuses are sampled.

Squaring the focus measurement values of the sampled _focus-the step of ^{_{(y 2 p n ... y 2}} p -1, y 2 p + 1 ... y 2 p + n) (S730) is performed. The reason for performing the squaring is to convert a negative value to a positive value because the focus measurement value may be negative. In some cases, it may be replaced by another scheme for amphiping. For example, taking the absolute value of the focus measurement of the sampled foci may be performed.

Summing the squared values of the plurality of focus of the reference focus before and ^{_{(S 0 = y 2 p -}} n + ... y 2 p -1), S ( for adding the squared value for a plurality of focus since the focus criteria ₁ = y ² _{p + 1} + ... y ² _{p + n} ) is performed (S740)

이다 (S750). 즉, 이 경우에 편향값은 -1보다 작은 음수로서 좌측 이동을 의미한다. 만약에, 분모인 S₀가 0인 경우에는 편향값은 0으로 결정된다. 여기서, 10은 편향 계수(A)로서 사용 환경에 따라서 다른 값으로 대체될 수 있다. As a result of comparison between S ₀ and S ₁ , when S ₁ is smaller than S ₀ , the deflection value is determined as max (-1, (R-1) * 10)

(S750). That is, in this case, the deflection value means a leftward movement as a negative value smaller than -1. If the denominator S ₀ is 0, then the deflection value is determined to be zero. Here, 10 can be replaced with another value depending on the use environment as the deflection coefficient (A).

이다 (S760). 즉, 이 경우에 편향값은 1보다 작은 양수로서 우측 이동을 의미한다. 만약, 분모인 S₁이 0인 경우에는 편향 값은 0으로 결정된다.As a result of comparing S ₀ and S ₁ , if S ₁ is _greater than S ₀ , the deflection value is determined as min (1, - (R-1) * 10)

(S760). That is, in this case, the deflection value means a rightward movement as a positive number smaller than one. If the denominator S ₁ is 0, the deflection value is determined to be zero.

On the other hand, according to steps S750 and S760 described above, the deflection value has a minimum value of -1 and a maximum value of 1. In the present invention, the reason why the deflection value is set in the range of -1 to 1 is as follows. The deflection value is a value for predicting the degree of deflection. If the value is smaller than -1 or larger than 1, the focus index will exceed the neighboring focus index.

As described above, according to the deflection value derivation method proposed by the present invention, it is possible to derive a deflection value using only basic linear equations such as square, addition, and comparison. According to the conventional technique, the calculation is very simple and the execution speed is improved as compared with the method using the high-order equation or the trigonometric function.

According to the deflection value derivation method proposed in the present invention, not all the focuses are calculated, but only a few focuses before and after one reference focus are calculated. Furthermore, the present inventor has found that even if the n value is 4 (i.e., when sampling four foci of the former four foci and a total of eight foci of the following four foci about the reference foci) And it is possible to achieve an optimal calculation speed.

On the other hand, the image subjected to the depth spreading includes a small amount of noise components. In order to remove such a small number of noise, a bilateral filter that suppresses noise while maintaining an important high-frequency signal can be applied.

The bilateral filter is non-linear, maintaining the edge and reducing noise.

The Binary Lateral filter uses a Gaussian distribution doubly and determines the basic distribution function -A by taking the distance from the center of each pixel in the convolution into a probability density function, The distribution function-B is determined by considering the difference between the brightness and the brightness of the center pixel. The distribution function -B is obtained by multiplying the distribution function-A by the brightness difference. The difference in brightness means the existence of the edge. Since the brightness is different as the edge is larger, the edge can be preserved.

The Binary Lateral filter is very complex because it has a double exponential function, and it handles all the pixels in the window for the line, so the throughput is very high. Therefore, the processing speed can be improved by processing the circuit loop in parallel.

Returning to the data processing step S140 of FIG. 1 again, the data processing step S140 includes image texturing processing. The image texturing process is to add detailed shapes, textures, colors, etc. to the objects in the 3D image. Referring to FIG. 12, an image in which image texturing is performed can be confirmed.

On the other hand, if the shaking of the oral scanner occurs above the reference using an accelerometer such as a gyroscope, the data processing step (S140) may not be performed. For example, assuming that the in-focus region is [A B] in the entire sweep range, you can get C in the middle. The positions of A and B are changed dynamically. However, if a prediction filter such as a Kalman filter is used, the position can be predicted. If the accelerometer shake information is reflected, the next in-focus area Can be predicted. This will reduce the scope of the measurement.

11 is a view schematically showing an oral scanner according to an embodiment of the present invention.

The mouth scanner 10 according to the embodiment of the present invention can be roughly divided into a main body 100, a head 200 and a cover 300.

The main body 100 includes an optical output unit 110, an image sensing unit 120, a control unit 130, and the like. In one embodiment, the main body 100 is formed to have a rectangular cross section, but the present invention is not limited thereto. For example, the main body 100 may be formed to have a circular or polygonal cross section.

The light output unit 110 irradiates light to the subject S in the oral cavity through a reflector, which is composed of a predetermined wavelength band, and may be installed at least one in front of the main body. As the light source, a laser, a light emitting diode (LED), a halogen lamp, an incandescent lamp, an infrared lamp, an ultraviolet lamp or a triple wavelength lamp may be selectively used. Although the optical output unit is described as being installed at the boundary portion between the main body 100 and the head 200 in one embodiment, the arrangement is not limited. For example, the light output unit 110 may be provided inside the head, or may apply pattern light in which a predetermined pattern is formed.

The image sensing unit 120 is installed in the front of the main body 100 and acquires an image formed by the reflected light reflected from the subject. That is, the image sensing unit 120 senses the reflected light reflected from the subject in the oral cavity by the light emitted from the light output unit 110, which will be described later, and uses a photo diode as a light receiving element and a charge coupled device Device as a charge transfer element or a CMOS image sensor which is a low power consumption type imaging element having a complementary metal oxide semiconductor (CMOS) structure can be used.

The control unit 130 controls the optical output unit 110 and the image sensing unit 120. For example, the control unit 130 transmits predetermined pattern information to the optical output unit 110, and performs signal processing and control operations on the data sensed by the image sensing unit 120. The control unit 130 receives the pattern information of the reflected light from the image sensing unit 120, and converts the pattern information into a three-dimensional image. The converted three-dimensional image can be displayed on a display unit (not shown).

이고, A는 편향 계수이다. 만약, 합산 결과 S₁이 S₀보다 큰 경우에, 제어부는 편향값을 min(1, -(R-1)*A)로 결정하고, 이 때,

이고, A는 편향 계수이다.In addition, the control unit 130 processes the acquired image. Specifically, the control unit 130 performs depth alignment processing, image spreading processing, curve fitting processing, bi-lateral filter processing, and image texturing processing. In addition, the controller 130 performs a deflection value calculation for the curve fitting process. Specifically, the control based on the focus has the maximum of the focus the focus (f _p) to set, and the reference focus (f _p) central to the previous plurality of focus in order to calculate the deflection values for the deflection correction processing (f _{p - n} samples a ... f _{p -1)} and a plurality of focus since the _{(p +} f ₁ ... f _{n + p).} Also, the control unit calculates the square of the focus measurement value of the sampled focus (y ² _{p - n} ... y ² _{p -1} , y ² _{p + 1} ... y ² _{p + n} ) (S ₀ = y ² _{p - n} + ... y ² _{p -1} ), and sums the squared values for a plurality of foci after the reference focal point. If the sum result S ₁ is smaller than S ₀ , the control unit determines the deflection value as max (-1, (R-1) * A). At this time,

And A is a deflection coefficient. If the sum S ₁ is _greater than S ₀ , the controller determines the deflection value as min (1, - (R-1) * A)

And A is a deflection coefficient.

The head 200 is installed in front of the main body 100 and is inserted into the oral cavity. The head 200 can be detachably coupled to the main body 100 to facilitate maintenance of the oral scanner. The head 200 may have a taper shape, which is gradually reduced in diameter toward the distal end so as to be easily inserted into the oral cavity, but may also be a straight shape.

An optical system 210 is provided in the main body 100 and the head 200. The optical system 210 is an aggregate of lenses or the like that irradiate the light output from the light output unit 110 to the subject and reflect the reflected light reflected from the subject to the image sensing unit 120, And a condenser lens 212 provided at the front of the image sensing unit 120. The condenser lens 212 may be a condenser lens,

The reflector 211 is provided at the front end of the head 200 to irradiate the light from the light output unit 110 to the subject or to reflect the light reflected from the subject to the condenser lens 212. The condensing lens 212 is installed in front of the image sensing unit 120 or in a separate lens support to collect the light reflected from the subject and guide the light to the image sensing unit 120. The optical system is designed at an appropriate angle, and can be configured to correct the angle as needed.

Such an optical system 210 includes a lens capable of moving the focus, and a method in which the focal length is changed by physically moving the lens may be used, and a method in which the focal length is adjusted by changing the surface shape of the fluid lens with voltage . Alternatively, the optical system 210 may be replaced on a stereo vision basis, in which case at least two or more liquid lenses may be positioned at either a horizontally or vertically symmetrical position.

The cover 300 is provided at the rear of the main body 100. For example, the cover 300 may be detachably coupled to the main body 100 by a method such as press-fitting or screw-coupling so that the parts in the main body 100 can be easily replaced or repaired.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims and their equivalents. Only. It is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents. .

In one or more exemplary embodiments, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, these functions may be stored or transmitted as one or more instructions or code on a computer readable medium. Computer-readable media includes both communication media and computer storage media including any medium that facilitates transfer of a computer program from one place to another. The storage medium may be any available media that is accessible by a computer. By way of example, and not limitation, such computer-readable media can comprise any computer-readable medium, such as RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, And any other medium that can be used to store and be accessed by a computer. Also, any connection is properly referred to as a computer-readable medium. For example, if the software is transmitted from a web site, server, or other remote source using a wireless technology such as coaxial cable, fiber optic cable, twisted pair cable, digital subscriber line (DSL), or infrared, radio and ultra high frequency, Wireless technologies such as fiber optic cable, twisted pair, DSL, or infrared, radio and microwave are included in the definition of media. Discs (Discs and Discs) as used herein include compact discs (CDs), laser discs, optical discs, digital versatile discs (DVD), floppy discs and Blu-ray discs, While discs reproduce data optically by laser. Combinations of the above should also be included within the scope of computer readable media.

When embodiments are implemented as program code or code segments, the code segments may be stored as a procedure, a function, a subprogram, a program, a routine, a subroutine, a module, a software package, a class, As well as any combination thereof. A code segment may be connected to another code segment or hardware circuit by conveying and / or receiving information, data, arguments, parameters or memory contents. Information, arguments, parameters, data, etc. may be communicated, sent, or transmitted using any suitable means including memory sharing, message passing, token passing, Additionally, in some aspects, steps and / or operations of a method or algorithm may be performed on one or more of the codes and / or instructions on a machine readable medium and / or computer readable medium that may be integrated into a computer program product As a combination or set of < / RTI >

In an implementation in software, the techniques described herein may be implemented with modules (e.g., procedures, functions, and so on) that perform the functions described herein. The software codes may be stored in memory units and executed by processors. The memory unit may be implemented within the processor and external to the processor, in which case the memory unit may be communicatively coupled to the processor by various means as is known.

In a hardware implementation, the processing units may be implemented as one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays Controllers, microcontrollers, microprocessors, other electronic units designed to perform the functions described herein, or a combination thereof.

What has been described above includes examples of one or more embodiments. It is, of course, not possible to describe all possible combinations of components or methods for purposes of describing the above-described embodiments, but one of ordinary skill in the art may recognize that many further combinations and permutations of various embodiments are possible. Accordingly, the described embodiments are intended to embrace all such alterations, modifications and variations that fall within the spirit and scope of the appended claims. Furthermore, to the extent that the term "comprises" is used in the detailed description or the claims, such terms are intended to be inclusive in a manner similar to "consisting" .

As used herein, the term " infer "or" inference "generally refers to a process of determining or inferring a state of a system, environment, and / or user from a set of observations captured by events and / It says. The inference may be used to identify a particular situation or action, or may generate a probability distribution for, for example, states. The inference can be probabilistic, that is, it can be a computation of a probability distribution for corresponding states based on consideration of data and events. Inference may also refer to techniques used to construct higher level events from a set of events and / or data. This inference may be based on a set of observed events and / or new events or operations from stored event data, whether the events are closely correlated in time, and whether events and data are coming from one or more events and data sources .

Furthermore, as used in this application, the terms "component," "module," "system," and the like are intended to encompass all types of computer- Entity. For example, a component may be, but is not limited to, a process running on a processor, a processor, an object, an executable execution thread, a program, and / or a computer. By way of illustration, both the application running on the computing device and the computing device can be components. One or more components may reside within a process and / or execution thread, and the components may be centralized on one computer and / or distributed between two or more computers. These components may also be executed from various computer readable media having various data structures stored thereon. The components may be associated with a signal having one or more data packets (e.g., data from a local system, data from another component of the distributed system and / or signals from other components interacting with other systems via a network such as the Internet) Lt; RTI ID = 0.0 > and / or < / RTI > remote processes.

10; Oral Scanner
100; A body 110; The light-
120; An image sensing unit 130; The control unit
200; Head 210; Optical system
211; Reflector 212; Condensing lens
300; cover

Claims (8)

A method of processing an oral image,
Imaging the interior of the mouth based on a plurality of foci;
Image-processing the photographed image; And
And outputting a three-dimensional image based on the image-processed image,
The step of image processing the photographed image comprises:
Performing curve fitting based on the plurality of foci; And
And calculating a deflection value for the deflection correcting process.
How to process oral images.
The method according to claim 1,
The step of calculating the deflection value
Setting a focus having a maximum focus measurement value as a reference focus f _p ; And
The reference focus (f _p) the center as in the previous plurality of _{focus-sampling} (f _p f _n ... _{p -1)} and a plurality of focus since the _{(p +} f ₁ ... f _{n + p)} Comprising:
How to process oral images.
3. The method of claim 2,
The step of calculating the deflection value
Squaring the focus measurement of the sampled focus (y ² _{p - n} ... y ² _{p -1} , y ² _{p + 1} ... y ² _{p + n} ); And
Summing squared values for a plurality of foci before the reference focal point (S ₀ = y ² _{p - n} + ... y ² _{p -1} ), summing squared values for a plurality of foci after the reference focal point S ₁ = y ² _{p + 1} + ... y ² _{p + n} )
How to process oral images.
The method of claim 3,
The step of calculating the deflection value
Determining the deflection value to be max (-1, (R-1) * A) if the sum result S ₁ is _less than S ₀ ,
here

A is the deflection coefficient,
How to process oral images.
The method of claim 3,
The step of calculating the deflection value
Wherein the deflection value is determined as min (1, - (R-1) * A) when the summing result S ₁ is _greater than S ₀ ,
here

A is the deflection coefficient,
How to process oral images.
3. The method of claim 2,
The step of image processing the photographed image comprises:
And performing a bi-lateral filter process for edge preservation and noise suppression of the video image.
How to process oral images.
A computer program stored on a medium for performing the method of any one of claims 1 to 6, when executed on a computer.
An apparatus for processing an oral image,
main body; head; And a cover,
Wherein the main body comprises: a light output part for photographing the inside of the oral cavity based on a plurality of focal points; An image sensing unit for acquiring a photographed image; And a control unit for controlling the light output unit and the image sensing unit,
The control unit includes:
Performing curve fitting based on the plurality of foci for the image to image the photographed image, and calculating a deflection value for deflection correction processing,
The deflection value based on the focus has the maximum value of the focus measurement to calculate the focus (f _p) as set by the reference focus (f _p) to the center of the previous plurality of focus (f _{p - n} ... f sampling a _{p -1)} and a plurality of focus since the _{(p +} f ₁ ... f _{n + p),} and
Focus measurement value of the sampled _{focus-square-on} (y ² ... y _{n p} ² _{p -1, p} ² ₊ y ₁ y ² ... _{p + n),} and a plurality of focus of the reference focus previous summing the squared values of the ^{_{(S 0 = y 2 p -}} n + ... y 2 p -1), summing the squared values of the plurality of focus since the focus criteria, and ^{_{(S 1 = y 2 p +}} 1 + ... y ² _{p + n} ),
The summation results S ₁ S ₀ is lower than the bias value max (-1, (R-1 ) * A) determined, and the summation result S ₁ to S ₀ is larger than the bias value min (1, - (R-1) * A)
And performing a bilateral filter process for edge preservation and noise suppression of the image image to image the photographed image.
Apparatus for processing oral images.

Images